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    //! Control register

    /// Control register
    #[derive(Clone, Copy, Debug)]
    pub struct Control {
        bits: u32,
    }

    impl Control {
        /// Returns the contents of the register as raw bits
        pub fn bits(&self) -> u32 {
            self.bits
        }

        /// Thread mode privilege level
        pub fn npriv(&self) -> Npriv {
            if self.bits & (1 << 0) == (1 << 0) {
                Npriv::Unprivileged
            } else {
                Npriv::Privileged
            }
        }

        /// Currently active stack pointer
        pub fn spsel(&self) -> Spsel {
            if self.bits & (1 << 1) == (1 << 1) {
                Spsel::Psp
            } else {
                Spsel::Msp
            }
        }

        /// Whether context floating-point is currently active
        pub fn fpca(&self) -> Fpca {
            if self.bits & (1 << 2) == (1 << 2) {
                Fpca::Active
            } else {
                Fpca::NotActive
            }
        }
    }

    /// Thread mode privilege level
    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub enum Npriv {
        /// Privileged
        Privileged,
        /// Unprivileged
        Unprivileged,
    }

    impl Npriv {
        /// Is in privileged thread mode?
        pub fn is_privileged(&self) -> bool {
            *self == Npriv::Privileged
        }

        /// Is in unprivileged thread mode?
        pub fn is_unprivileged(&self) -> bool {
            *self == Npriv::Unprivileged
        }
    }

    /// Currently active stack pointer
    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub enum Spsel {
        /// MSP is the current stack pointer
        Msp,
        /// PSP is the current stack pointer
        Psp,
    }

    impl Spsel {
        /// Is MSP the current stack pointer?
        pub fn is_msp(&self) -> bool {
            *self == Spsel::Msp
        }

        /// Is PSP the current stack pointer?
        pub fn is_psp(&self) -> bool {
            *self == Spsel::Psp
        }
    }

    /// Whether context floating-point is currently active
    #[derive(Clone, Copy, Debug, Eq, PartialEq)]
    pub enum Fpca {
        /// Floating-point context active.
        Active,
        /// No floating-point context active
        NotActive,
    }

    impl Fpca {
        /// Is a floating-point context active?
        pub fn is_active(&self) -> bool {
            *self == Fpca::Active
        }

        /// Is a floating-point context not active?
        pub fn is_not_active(&self) -> bool {
            *self == Fpca::NotActive
        }
    }

    /// Reads the CPU register
    #[inline]
    pub fn read() -> Control {
        match () {
            #[cfg(cortex_m)]
            () => {
                let r = match () {
                    #[cfg(feature = "inline-asm")]
                    () => {
                        let r: u32;
                        unsafe { asm!("mrs $0, CONTROL" : "=r"(r) ::: "volatile") }
                        r
                    }

                    #[cfg(not(feature = "inline-asm"))]
                    () => unsafe {
                        extern "C" {
                            fn __control() -> u32;
                        }

                        __control()
                    },
                };

                Control { bits: r }
            }

            #[cfg(not(cortex_m))]
            () => unimplemented!(),
        }
    }

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